Yes, the -10 is a big plane, with more rivets and parts count in general. Even so, I would expect airframe completion to take not much more time than say, a current -7 or -9 kit. Really, the airframe isn't the major equation. The systems, FWF, interior, panel, paint stuff can really suck up a lot of time when you look at the big picture. After my RV8 airframe was basically done, it seemed to take ages to get through all the other stuff. I was almost longing to see my rivet gun again!
For me, the big difference in the -10 vs. the two seaters is cost. That's why I'm not going to finish my RV10. To properly dress and equip an RV10 for it's intended mission is not an inexpensive endeavor. A very functional, light and fast two holer RV can be built for $50k or even less. The -10 with well-appointed panel, interior, paint and engine/prop will go easily over $100k.
I would not let the airframe size and build time deter you from the -10 if that is really what you need for your mission. Once you get drilling, deburring, riveting....what's a few thousand more rivets when you're looking at over 10,000 of them to begin with? If you really are in a hurry to get flying, then slow build kit maybe isn't the right approach. Go the QB route. We're seeing -10's completed in two years...maybe less? It took me 30 months to get my non-matched hole RV8 flying with VERY dedicated effort. I attacked it like a second job, and this was before kids. Given the same conditions today, I could have a -10 flying in the same time, even though it's a lot bigger. You no longer have to build jigs. My -10 empecone kit was incredibly easy to build. I just nibbled away at it a few hours per week and it just fell together. Simply amazing kit from the brilliant minds at Van's.
If you're the average working Joe; kids, baseball, ballet, job, house, wife, LIFE, then come to grips with the fact that you'll need 3-5 years to build. That applies to most any airplane. The matched hole kits just improve the odds that you'll still have your sanity when it's all over.